Muffler with plural side branch chambers



Sept. 4,

H. R. JOHNSON 2,556,939

MUFFLER WITH PLURAL SIDE BRANCH CHAMBERS Filed May 2, 1950 patentedSept. 4, 195i OFFICE MUFFLER WITH PLURAL SIDE BRANCH CHAMBERS Howard R.Johnson, Pound, Va.

Application May 2, 1950, Serial No. 159,413

8 Claims. (Cl. 181-48) This invention relates generally to soundmuiilers or silencers particularly of the type suitable for use with theexhaust system of an internal combustion engine and has for itsprincipal object the provision of a simpler and more eincient muiiier.

It is a primary object of the invention to provide a light weight mulerof simple construction which will be highly effective as a silencer butwhich will minimize to a surprising degree the objectionable backpressure on the motor.

A still further object of the invention is to provide a silencer inwhich the exhaust gases are divided into two parts so that each one ofthe two parts can now thru alined openings.

In the drawings:

Figure 1 is a central axial section.

Figure 2 is a plan view of a washer.

Figure 3 is a transverse section thru the muiller with the partition inplace but omitting the baiiies.

Figure 4 is an elevation of the central strip.

In the drawings the numeral I is a cylindrical pipe of normal size andlength for the purpose having at its iront end the head II, having aninlet opening I2 surrounded by a nipple I4, a suitable size is about 5"in diameter and about three quarters of a yard long.

The central strip I5 is a metal sheet the length of the muiiler andfitting snugly from top to bot- 5 tom but having a plurality of notchesIB in its top edge. The central partition I5 divides the interior of thepipe In into two equal spaces I1 and I8 preferably unrestricted.

Within the pipe IU I mount a plurality of washers or bales each fittingfairly snugly within the pipe and having a central slot 2l to receivethe dividing sheet I5 and having on each side of the slot an opening 23and 24 each shaped as shown in the drawings and preferably having anarea equal to the area of the entrance opening I2. It will be noted thatthe holes are all of the same size and by virtue of the slot and notchconnections all of the holes 23 are alined and all of the holes 24 arealined. The inner curve 25 of the two openings together form a circularbaiile 26 and the proximate edges 21 of the openings 23 or 24 are spacedappreciably from the dividing partition or strip so that the openings 23and 24 are roughly centrally positioned in the passageway I1 and I8.

In order to achieve the greatest amount of reduction of sound I iind ithighly advantageous to space the baiiles 20 so as to form the chambers,such as 30, 3|, 32, 33 and 34, in constantly decreasing axial lengths. Iprefer that the initial chamber 30 shall be greater than the diameter ofthe pipe, the second chamber 3| approximately the diameter of the pipe,the third chamber 32 about half the diameter of the pipe, and the axiallengths of the next two chambers 33 and 34 should be reducedconsecutively by a half inch. The net result of this is that the muiiiercan be used under different conditions and with different engines andwill silence all of these whereas if the bales 20 were equally spacedthe result would be far less eicient. I also nd that by increasing theaxial length of chamber 35 over that of 34 and again increasing theaxial length o f the next chamber 36, superior results are obtained andin the preferred model I add a chamber 31 of very short axial length andfollow this with a chamber 38 which is only a trie shorter than theaxial length of chamber 36. The ratio of the chambers beginning at theinlet end will be 12:10:5:4:3:4:8:2:7.

For ease in manufacturing I prefer to have the strip I5 and the varioustransverse baiiles or disks 20 formed as a unit and it is also mypreference to weld the washers to the strip before insertion in thetube. Sometimes I weld the unit lightly or crimp the end ofthe tube I0to insure against rattling and yet have the unit removable with verylittle trouble.

The mufer under test runs remarkably cool and the back pressure isconsiderably less than 2" of mercury at 50 miles per hour. As an exampleof the eiiiciency of the device, a standard car was driven up a hill andit slowed down to 15 miles per hour at the top when using its ownmuiiler. On using the muilier of the present invention, however, the carwas still going 28 miles per hour as it crossed the top.

What I claim is:

1. A muiiler including a cylindrical casing with a restricted inletopening, a flat partition strip lonigtudinally dividing the casing intotwo equal portions, and a plurality of transverse baies substantiallyclosing the casing and forming chambers, each baille having therethru apair of openings of equal area, one in each longitudinal portion, thebaiiles being secured to the partition strip so the strip and thebaffles may be removed as a unit from the casing.

2. The muiiier of claim 1 in which the strip is notched, the baiiles aredisks each having a central slot to receive the strip and to be held inthe notches, and the openings are spaced from the strip and from thecasing.

3. A muler including a casing having a re 3 stricted inlet opening, afiat partition strip longitudinally dividing thecasing into two equalportions, and a plurality of transverse baffles closing the casing andforming chambers, each baie having therethru a pair of openings, one neach longitudinal portion, the several openings on each side of thestrip being alined.

4. The device of claim 3 in which the area of each of the openings isequal tothe area of the inlet. Y

5. The muier of claim 3 in which the axial lengths of the chambersformed by the baflies decrease in regular order from the inlet end to amidpoint and then increase in axial length.

6. The muffler of claim 1 in which there are at 1.

least eight baies spaced to form chambers of at least seven differentaxial lengths. v

7. The muflier of claim 1 in which the axial 4 length of the chamberbetween the inlet and the iirst baille is more than one sixth of thelength of the shell and the ratios of the successive chambers is12:10:5:4:3.

8. A muffler having a series of at least six transverse perforated bafesforming chambers of diierent axial lengths, the nal chambers having theratio 4:8:2:7, the diameter of the muffler at the same scale beingapproximately 10.

HOWARD R. JOHNSON.

Name Date Mason Aug. 30, 1932 Number

